1. Field of the Invention
The present invention relates to an image recording apparatus which performs image recording on a recording medium.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2010-162804 discloses an image formation apparatus which performs image recording by an ink-jet head which jets ink from nozzles while reciprocating in a scanning direction. In the ink-jet head disclosed in Japanese Patent Application Laid-Open No. 2010-162804, black nozzles are aligned at intervals which are half of intervals of color nozzles. When both black ink and color inks are used to perform image recording, a series of operations are repeatedly carried out. That is, the ink-jet head is moved in the scanning direction while jetting the inks from the black and color nozzles, and then recording paper is transported by the length of five intervals of the black nozzles.
In this case, in the ink-jet head disclosed in Japanese Patent Application Laid-Open No. 2010-162804, the black nozzles are arranged such that they are divided into two black nozzle groups and, on each timing of ink-jetting, the ink is jetted alternately from the black nozzles belonging to one of the two groups and from the black nozzles belonging to the other. By carrying out image recording in this manner, while moving the ink-jet head once in the scanning direction, all of the black nozzles have a chance to jet the ink, and hence it is possible to prevent the black nozzles from drying.
In the image formation apparatus disclosed in Japanese Patent Application Laid-Open No. 2010-162804, such a case is conceivable as recording a straight line extending in a direction perpendicular to the scanning direction. In a case that such a line is recorded by using the image formation apparatus disclosed in Japanese Patent Application Laid-Open No. 2010-162804, as will be described hereinafter, the dots forming the line become smaller, and thus light line is recorded.
Further, in the ink-jet head disclosed in Japanese Patent Application Laid-Open No. 2010-162804, the black nozzles are aligned at intervals which are half of the intervals of the color nozzles. However, for the purpose of raising the speed of recording black-and-white images, it is also conceivable to further reduce the interval between the black nozzles so as to align the color nozzles at intervals each of which is not less than three times and an odd multiple of each of the intervals of the black nozzles. Then, in such cases, the dots forming a straight line become even smaller, and thus the line is recorded more lightly.